Electrochemical Reduction of CO 2 on Nitrogen‐Doped Carbon Catalysts With and Without Iron

The carbon dioxide reduction reaction (CO 2 RR) catalyzed by N‐doped carbon materials was studied under operando conditions by on line differential electrochemical mass spectrometry and in‐line gas chromatography. Fe/NC electrocatalysts were synthesized by using a Fe +2 ‐impregnated pyridyl/triazine complex heat treated at 800 °C in nitrogen (Fe/NC(N 2 )) or ammonia (Fe/NC(NH 3 )) atmospheres; an iron‐free nitrogen‐doped carbon electrocatalyst (NC(NH 3 )) was also synthesized and included for comparison. Here, superior CO faradaic efficiencies were evidenced for NC(NH 3 ) compared to Fe/NC(NH 3 ), independently of the applied electrode potential; however, much larger overall catalytic activity for the promotion of the CO 2 RR and/or HER has been observed for Fe/NC(NH 3 ), generating different stoichiometric ratios of syngas (CO/H 2 ). Another important evidence is that N‐pyridinic groups, even in absence of Fe−N 4 moieties and presence of high iron nanoparticles loading, play an important role as active sites for selective CO 2 reduction to CO at low overpotentials.